RSC Applied Polymers最新文献

Emerging battery technologies such as solid-state sodium batteries can benefit from new polymer electrolytes with improved sodium ion transport to optimise electrochemical performance. In this work, we propose, for the first time, the use of polyelectrolyte blends utilising a dual cation approach with a common polyanion backbone, poly(1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethanesulfonyl)imide) (polyMTFSI). Thus, three new anionic polyelectrolytes were synthesised based on polyMTFSI having three different counter cations such as sodium (Na) (polyMTFSI-Na), trimethyl(isobutyl)phosphonium (poly-MTFSIP_111i4) and diethyl (isobutyl)(methyl)phosphonium (polyMTFSI-P_122i4). The miscibility between the polyelectrolytes in blends was determined by observing a single glass transition, T_g, for different compositions. Upon the addition of bulky organic cations, an increase in the dynamics and ionic conductivity was observed. Finally, we investigated the effect of NaFSI as an additional component in a ternary electrolyte system, whereby the salt acted as a plasticizer, decreasing T_g, and further enhancing the ionic conductivity.

Ring-opening polymerization (ROP) is a powerful method for the synthesis of biocompatible and biodegradable polyester-based amphiphilic block copolymers, which are an excellent nanomaterial class for a wide range of pharmaceutical applications. These block copolymers are synthesized using a catalyst, which is typically purified out. In a separate step, the purified block copolymers are then assembled and drug-loaded for medical use. This multistep process limits the scalability of these nanomaterials restraining their industrial use. Recently, we developed a synchronous polymerization and self-assembly process for polyester-based block copolymer nanomaterials coined Ring-Opening Polymerization-Induced Crystallization-Driven Self Assembly (ROPI-CDSA). In ROPI-CDSA, an organocatalyst facilitates the chain extension of mPEG with L-lactide, yielding semicrystalline self-assemblies. Here, we demonstrate that pharmaceuticals with similar functional groups to ROP organocatalysts can catalyze ROPI-CDSA reactions, resulting in the formation of drug-embedded nanomaterials. The major advantage of this one pot approach is that no additional synthetic steps or purification are required. As a proof-of-principle study, we use two antibiotic drug molecules, chlorhexidine, and trimethoprim, as catalysts. Chlorhexidine acts as a co-initiator and a catalyst leading to drug conjugation whereas trimethoprim acts solely as a catalyst leading to drug encapsulation. The resulting drug-embedded block copolymer nanoparticles retain potent antibacterial activity. We anticipate that this strategy can be extended to other examples of PISA for the scalable production of drug-loaded polymer suspensions.

Cellulose nanocrystals (CNCs) are sustainably sourced, non-toxic, high-strength nanoparticles most often derived from wood pulp. The incorporation of CNCs into latexes via in situ semi-batch emulsion polymerization has been shown to improve the performance of latex nanocomposites, specifically latex-based pressure sensitive adhesives (PSAs). A bench-scale study was designed to compare the effect of incorporating CNCs with different surface chemistries and dispersion quality on the final latex properties, film formation, and adhesive performance. Poly(butyl acrylate/methyl methacrylate)-CNC latex nanocomposites (at 40 wt% solids) were successfully synthesized with 1 wt% sulfated CNCs and carboxylated CNCs (DextraCel™) with different storage methods (never-dried suspension vs. dried powder). All CNCs were well-dispersed in water using probe sonication prior to being incorporated into the latex polymerization reactions. Extensive characterization revealed differences in the latex and PSA film properties, with never-dried carboxylated CNCs and dried sulfated CNCs having the highest viscosities, lowest relative colloidal stabilities by visual inspection, and most enhanced adhesive performance. Additionally, PSA films containing dried carboxylated CNCs exhibited the greatest latex particle coalescence, as measured by atomic force microscopy, which correlated to improved cohesive strength. The ability to tune latex properties with CNCs may facilitate the widespread use of “greener” water-based polymerization methods, even for applications outside of adhesives, such as paints, coatings, inks, toners and rubbers.

Chemical recycling of polymers is one of the biggest challenges in materials science. Recently, remarkable achievements have been made by utilizing polymers prepared by controlled radical polymerization to trigger low-temperature depolymerization. However, in the case of atom transfer radical polymerization (ATRP), depolymerization has nearly exclusively focused on chlorine-terminated polymers, even though the overwhelming majority of polymeric materials synthesized with this method possess a bromine end-group. Herein, we report an efficient depolymerization strategy for bromine-terminated polymethacrylates which employs an inexpensive and environmentally friendly iron catalyst (FeBr₂/L). The effect of various solvents and the concentration of metal salt and ligand on the depolymerization are judiciously explored and optimized, allowing for a depolymerization efficiency of up to 86% to be achieved in just 3 minutes. Notably, the versatility of this depolymerization is exemplified by its compatibility with chlorinated and non-chlorinated solvents, and both Fe(II) and Fe(III) salts. This work significantly expands the scope of ATRP materials compatible with depolymerization and creates many future opportunities in applications where the depolymerization of bromine-terminated polymers is desired.

Non-fossil feedstocks for the production of photocurable resins have attracted growing interest from the scientific community and industry in order to achieve more sustainable 3D-printing technologies. Herein, we report the successful photopolymerization process of three diallyl ester monomers, derived from succinic acid, D,L-malic acid and L-(+)-tartaric acid (natural acids), with poly(ethylene glycol) diacrylate, a petroleum-based co-monomer well-known for its fast UV light reaction response. The existence of hydroxyl groups beside the ester units in the malic and tartaric compounds did not influence either the kinetics or the thermal stability of the thermoset polymers. Therefore, the most prominent composition was formed by 50 wt% of the bio-derived diallyl succinate, and 50 wt% of the synthetic, having excellent thermal stability and very good dimensional resolution and transparency in DLP printed samples after light curing, and most importantly, such samples promptly undergo hydrolytic degradation thanks to the presence of the ester linkages that are incorporated by the natural monomer.

A concept for an on-demand linerless pressure sensitive adhesive (PSA) label is shown. Containment of a PSA has been achieved by entrapment within a scaffolding 3D hard mesh structure. The label sticks upon instant application of heat and pressure, which softens and deforms the mesh allowing for PSA release. The design eliminates the need for a release liner and release coating in labels offering a more sustainable product. Herein, the mesh-reinforced PSA system was made by film formation of a binary polymer latex mixture consisting of ‘hard’ (high glass transition temperature, T_g,hard) polystyrene particles and a ‘soft’ (low glass transition temperature T_g,soft) poly(n-butyl acrylate)-based PSA latex of similar particle diameter, onto a model polyethylene terephthalate (PET) facestock. The system was annealed above T_g,hard to fuse the polystyrene colloids, creating a 3D interconnected open cellular network. The porous scaffold was shown by scanning electron microscopy, X-ray computed tomography, and confocal microscopy. The linerless PSA label is in a dormant, ‘non-stick’ state at room temperature, showing excellent blocking resistance under storage conditions. Adhesion is activated on demand with heat (T > T_g,hard) and light pressure. The adhesive behavior of the linerless PSA labels was probed using peel, shear strength and tack, its performance being promising.

This study investigates DLP 3D printing using RAFT polymerization-induced self-assembly (RAFT PISA) printing, focusing on the impact of CTA (chain transfer agent) groups per scaffold on PISA printing times and mechanical properties of printed objects. We synthesized a solvophilic polymer scaffold from DMA (N,N-dimethylacrylamide) and HEAm (2-hydroxyethyl acrylamide) in a 90 : 10 molar ratio, suitable for CTA functionalization and solubility in various solvents. Employing an aqueous, oxygen-tolerant PET RAFT process, we achieved a target degree of polymerization (DP) of 10 000, introducing varying amounts of CTA groups by esterification (chain transfer agent functionalized scaffold or CFS), with the highest graft density resulting in a scaffold with an average of 74 CTA groups. This process was additionally repeated with a DP 500 scaffold by grafting with varying densities of CTAs. Photocurable DLP (digital light projection) resins based on the chain extension of core-forming DAAm (diacetone acrylamide) from the CFS macro-CTA were then prepared and used to print 3D objects. This study revealed that the increased number of CTA groups per scaffold decreased the normal exposure time for PISA printing when compared to our previous work which employed a difunctional macro-CTA. In mechanical property assessments, conducted across different DPs and CTA graft densities, we observed trends in modulus, strain-to-break, and toughness. The increasing modulus trend ceased beyond a DP of 500, suggesting a balance between the amounts of DAAm and CTA-functional scaffolds. Additionally, parts with higher graft densities demonstrated increased stiffness due to a higher density of physical crosslinks. The study also explored the dissolution behavior of these parts in DMF, with parts showing varying degrees of swelling and dissolution depending on their DP and CTA graft density. These findings indicate a significant advancement in the 3D PISA printing technique, offering new insights into the optimization of printing times and mechanical properties, potentially revolutionizing applications in areas like biomedical implants and tissue engineering scaffolds.

Cellulose nanofibrils (CNFs) were surface modified with poly(methyl methacrylate) (PMMA) in water by a grafting-through surfactant free emulsion polymerization scheme resulting in reinforcements that could be straightforwardly dried while maintaining a high specific surface area. These PMMA modified CNFs contained 40 wt% PMMA, could be filtered to remove most the of water, and subsequently dried under vacuum to yield powders that could be directly used as reinforcements for composites. The PMMA modification prevented fibrillar collapse upon drying yielding high specific surface area (ca. 50 m² g⁻¹) and surface energy similar to PMMA. Once melt compounded into PLA, PMMA modified CNFs led to composites with a tensile strength of 79 MPa, a nearly 30% increase over neat PLA, at 20 wt% loading of the reinforcement. The mechanism of improvement was attributed to the improved interfacial compatibility between the PMMA modified CNFs and the PLA as confirmed by surface energy measurements and the ability of the reinforcement to disperse within the PLA matrix as confirmed by imaging and rheological measurements. Overall, this work demonstrates that a scalable water-based modification can be used to create CNF reinforcements for PLA composites that significantly improve mechanical properties without complex drying and solvent exchange processes.

Electrospinning is a highly versatile method for manufacturing filter membranes, contributing to advanced concepts for the production of sustainable membranes for waste water treatment. The use of bio-based polymers could expand the sustainability of such filter membranes significantly. Bio-based PA 6.9, for example, shows great potential for the creation of bio-sourced electrospun filter membranes (EFMs) with high mechanical properties and high resistance to solvents. The polyamide is synthesized from plant oil-based azelaic acid and electrospun from chloroform/formic acid to produce self-standing electrospun nonwovens. These highly porous membranes show high efficiencies of up to 99.8% for the filtration of polystyrene microparticles (PS-MPs) from water. Additionally, the electrospun nonwovens exhibit comparable filtration efficiencies to FFP3 masks for the removal of 0.3 μm particles from air. The membranes show hydrophobic surface behavior (water contact angle of >120°) making them suitable for water oil separation. Efficiencies of up to 99.9% can be achieved for the separation of water and chloroform from 50 vol% mixtures, while maintaining a high permeate flux of up to 5345 L m⁻² h⁻¹. Additionally, the membranes can be reused for at least ten times without any significant reduction in efficiency or flux.

Multi-component structured filaments offer the potential for enhanced mechanical performance in 3D printed plastics. Here, the interactions between filament components in the core (polycarbonate, PC)–shell (polypropylene, PP) geometry are manipulated by light maleation (1%) of PP to understand how the inclusion of favorable polar interactions and potential grafting reactions at the core–shell interface impact the mechanical performance of the 3D printed parts. The elastic modulus of the 3D printed tensile bars is essentially independent of the shell selection for the fully isotactic PP (iPP) or maleated PP (miPP), but the strain at break is generally significantly improved with the miPP shell to increase the toughness of the printed parts for both flat and stand-on build orientations. This is counter to compression molded specimens where iPP is more ductile than miPP. The mechanical behavior in the flat orientation is consistent with long fiber composites, where the PC core essentially acts as fiber-reinforcement. Tribo-testing results indicate increased friction between miPP and PC through the interaction of the maleate anhydride group with the carbonate relative to the iPP with PC. This small increase in the interfacial interaction between the core and shell polymers with miPP increases the work required to pull out fibers of the stiffer PC from the PP matrix for the flat build orientation and more energy is required to delaminate the core from the shell, which is the loci of failure, when the stand-on build orientation is stretched. The subtle change in chemistry with a maleation of 1% of PP leads to a larger strain at failure and tougher parts due to the interaction with PC. These results illustrate that the selection of the polymers in structured filaments needs to also consider their potential intermolecular interactions including the potential for grafting reactions to best enhance the mechanical response of 3D printed parts.